(i) Technical Field
The present invention relates to a flexible optical waveguide film, an optical transceiver module, a multi-channel optical transceiver module, and a method of manufacturing a flexible optical waveguide film. Particularly, the invention relates to a flexible optical waveguide film, an optical transceiver module, and a multi-channel optical transceiver module having a low profile or size and a method of manufacturing a flexible optical waveguide film which allows manufacturing steps to be simplified.
(ii) Related Art
Various methods for manufacturing a polymer optical waveguide have been proposed in the related art including, for example:
(1) a method in which films are impregnated with a monomer and in which the films are combined with the refractive index of a core part varied by selectively exposing the same (selective polymerization method);
(2) a method in which a core layer and a clad layer are applied, and a clad part is thereafter formed using reactive ion etching (RIE method);
(3) a method in which an ultraviolet curable resin provided by doping a polymeric material with a photosensitive material is exposed and developed using photolithography (direct exposure method);
(4) a method utilizing injection molding; and
(5) a method in which a core layer and a clad layer are applied, and a core part is thereafter exposed to change the refractive index of the core part (photo-bleaching method).
However, the selective polymerization method of the above item (1) has a problem when films are combined. The RIE method of the above item (2) and the direct exposure method of the above item (3) result in a cost increase because a photolithographic process is used. The injection molding method of the above item (4) has a problem with the accuracy of the diameter of a core obtained by the method. The photo-bleaching method of the above item (5) has a problem in that a sufficient difference cannot be obtained between the refractive indices of a core layer and a clad layer. Although the RIE method of the above item (2) and the direct exposure method of the above item (3) may be regarded as practical methods providing high performance, they have a problem with manufacturing costs as mentioned above. Any of the manufacturing methods of the above items (1) to (5) is practically unsuitable for the formation of a polymer optical waveguide on a plastic substrate which has a great area and which is flexible.
In the field of IC techniques and LSI techniques, attention is recently paid on the implementation of optical wiring between apparatus, between boards in an apparatus, or in a chip instead of providing electrical wirings in a high density in order to achieve an improved operating speed and an improved level of integration. In particular, various proposals have been made on elements for optical wiring which utilize a surface emission laser and a photo-diode that is a surface light receiving element to take their advantage in reducing power consumption and forming a planar array.